Gerotor pump or motor device with rolling support

ABSTRACT

A gerotor or pump or gear device includes a stationary housing having a chamber with an outer ring gear and inner rotor. The outer ring gear is supported by rolling elements between the housing and outer ring gear and is rotatable about a center axis. The inner rotor is fixed to a shaft and rotatable therewith about a shaft axis that is offset or eccentric relative to the central outer ring gear axis.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. Utility Patent Application claims priority to U.S. Provisional Patent Application No. 62/780,596, filed Dec. 17, 2018, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Technical Field

This invention relates to gerotor pumps or motors.

2. Related Art

Gerotor pumps and motors typically have a fixed housing in which an outer ring gear and inner rotor are received. The outer ring gear slides relative to the housing and the inner rotor is fixed on an off-center shaft. Relative rotation of the inner rotor and outer ring gear causes their teeth to mesh and creates spaces of decreasing and increasing volume. Fluid introduced to the device is caused to be pumped through the changing spaces or to drive the inner rotor and shaft, in the case of a motor.

The sliding support of the outer ring introduces drag and inefficiencies to gerotor devices.

BRIEF SUMMARY OF THE INVENTION

A gerotor pump or motor device according to one aspect of the invention includes a housing, an outer ring gear, and an inner rotor mounted on a rotatable shaft. The outer ring gear is supported for rotation relative to the housing by rolling elements. Such reduces drag between the outer ring gear and housing and improves efficiency.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

These and other features and advantages of the invention will be better understood when considered in connection the accompanying description and drawings, in which:

The sole FIG. 1 is a schematic cross-sectional view of a gerotor pump or motor device in accordance with a representative embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A gerotor pump or motor device 10 in accordance with an embodiment includes a stationary housing 12 having a chamber 14 with a cylindrical inner wall centered about an axis A.

An outer ring gear 16 is disposed within the chamber 14 and shares the center axis A. The outer ring gear 16 is formed with a plurality of inner teeth 18 numbering X (e.g., 6). The outer ring gear 16 is rotatable relative to the housing 12.

An inner rotor 20 is also disposed within the chamber 14 and within the outer ring gear 16. The inner rotor 20 is mounted on a shaft 22 for rotation therewith. The shaft 22 and inner rotor are supported by the housing 12 for rotation within the chamber 14 about a shaft axis B. The shaft axis B is offset relative to the center housing axis A. In other words, the shaft 22 and inner rotor 20 rotate within the chamber about axis B that is off-center in relation to the axis A about which the outer ring gear 16 rotates.

The inner rotor 20 has a plurality of outer teeth 24 numbering X−1 (e.g., 5). The outer teeth 24 are in meshing contact with the inner teeth 18 of the outer ring gear 16. Rotation of the inner rotor 20 and outer ring gear 16 (in either a pump or motor format) cause the teeth 18 and 24 to roll and slide past one another to create spaces of variable and dynamically changing volume during operation. Fluid introduced to the chamber 14 passes through these spaces and, in a pump format, is thereby pressurized to pump or move the fluid from an inlet port 26 through an outlet port 28 in the housing. In a motor format, pressurized fluid introduced to the chamber serves to drive the rotor 20 and effect rotation of the shaft 22.

According to a particular aspect of the invention, the rotatable support for the outer ring gear 16 is provided by a plurality of rolling elements 30 disposed between the housing 12 and outer ring gear 16. The elements 30 may take the form of needle or roller bearings or ball bearings. Rolling rather than sliding support of the outer ring gear is believed to reduce friction and increase efficiency of the device 10.

The above illustrated and described embodiments are intended to be representative but not limiting of the invention. The invention is defined in the accompanying claims.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically described while still being within the scope of the invention. 

What is claimed is:
 1. A gerotor pump or motor device, comprising: a stationary housing having an inner chamber; an outer ring gear disposed within the chamber and rotatable relative to the housing about a center axis A, the outer ring gear having a plurality of inner gear teeth; a shaft; an inner rotor mounted on the shaft, the shaft and the rotor being supported by the housing for rotation about a shaft axis B that is offset relative to the center axis, the inner rotor having a plurality of outer teeth that engage the inner teeth of the outer ring gear; and wherein the rotatable support for the outer ring gear is provided by a plurality of rolling elements disposed between the housing and outer ring gear.
 2. The device of claim 1 wherein the rolling elements comprise either roller bearings, needle bearings or ball bearings. 